How much knock is ok????

[84wh1]

Just want to know, how much knock is ok?

I floored it yesterday and I got 7.1 degrees of knock! That seemed very high to me, so I instantly let off the gas.

Also, I tried to nail it again after that, and the car started to sort of let off or bog very lightly, Could that have been the computer letting off because I was detonating when I last floored it.?

BTW, I had a TRASHER 100 chip in the car and I was using a 114(2gal)/92 oct(3gal). mix.

Thanks

 

[crazygn]

Was this from a dead stop or did you floor it from a get go and it down shifted. Mine would do it on down shifts real bad when i first got it , tell i found that it was bad to do with these cars

I would think that would be high for the 114 fuel mix your running, what was your boost.

 

[84wh1]

Yea, I punched it at about 35mph and i'm not to sure what kind of boost I was running because I was over focused at the scanmaster, but when I was knocking at 8deg, the boost was only at about 12pounds.

I'll go out tomorrow and take it for a spin to check it out again.

 

[84wh1]

Well, I drove my car agin today, and I checked my O2s. They were at about 775-825. Boost was only at about 15 pounds, but thats with the wastgate all the way down. And I was also getting about 5.9 degrees of knock.

How can I get knock with 100 oct(est) in the tank and only 15 pounds of boost. Fuel pressure was at about 39 pounds.

Also, how come i only got 15 pounds of boost?

BTW, I also now have a thrasher 92 in the car and the other day, I got 14 deg of knock when I puched it from a dead stop, I also heard a POP.




Thanks

 

[Brent]

NO knock is ok. Just a thought but w/ the 87 ecm and chips they are for max performance w/ some kind of intercooler what about running straight 114 or running 114 w/92 chip? Have been thinking of ecm swap my self, but wondering about this or if i needed custom chips? Dont take this to heart is just a thought, mabey I'm way off base.

(its not in my sig) 84 T-Type 36#inj, cam, ported heads, afpr, booster pump, headers,straight exhaust, chip, k&n, cold air, tb lines,160*t-stat, forged pistons, total seal ringes, other misc. stage 1 internals ,10.4 wires, ngk plugs, 2 1/2 down pipe, 87mod and coil, breather, 3:73 posi, 275/60 cheater slicks

 

[crazygn]

What kind of fuel , i here that there are some fuels that should not be ran in these cars because they make more knock then others ,


just a thought

 

[84wh1]

The fuel thats in the car is C14 and Esso(exxon) 92

What other kind of things could cause knock?

Maybee i'm getting more boost than my guage reads because its not hooked up tight enough, but then again, my O2s would be higher than 800? Right?

 

[crazygn]

Could be the gauge or false knock, i think if it was at a higher boost your o2's would be lower because your adding more air and would need more fuel to up your 02's , help out guys.What is the timing on that chip that you are running.

 

[dave84gn]

Hey Marc! Strange problem, but it's probably tuning related (isn't everything, grr!). Gota play with settings and see how things change. My guess is it has something to do with the chip being programmed for an intercooled car. Perhaps the fuel curve is significantly different for 87s ? I'm not sure.

What are your BLMs? Can the scanmaster tell you that? Anything below 128 means the ECM is pulling fuel because it's running rich and anything above means the opposite. So if your BLMs are below 128, lower your fuel pressure. Otherwise, try raising it.

Oh and just because you see O2's in the 800s at WOT doesn't mean you are running those O2's all the time. Since the chip probably has a different fuel curve than what your car likes, it may be running lean near the bottom end of the curve (before WOT), and causing knock. I don't really know, that's a pretty big stretch though.

Play with the fuel pressure and boost and see what you can come up with. And did you say you can't lower your boost any more? That's strange.. Mine is at 13psi right now and it goes much lower. Oh well, who knows.

Keep at it!

Dave